The whole "petrificatiom beam that turns people into stone, keeps them on suspended animation for several thousand years, and heals all injuries" concept that the story is based around is clearly fictional. We don't know how to replicate most of that with even theoretical science.

The A.I. on the International Space Station is more advanced than anything we can make right now.

Also, the recent manga chapters indicate that apparently there is someone living on the moon that is behind the original stone beam, and they may or may not be nonhuman (i.e., aliens). Sapient aliens aren't impossible, but we don't know of any right now.

The whole "petrification beam that turns people into stone, keeps them on suspended animation for several thousand years, and heals all injuries" concept that the story is based around is clearly fictional. We don't know how to replicate most of that with even theoretical science.

The A.I. on the International Space Station is more advanced than anything we can make right now.

Also, the recent manga chapters indicate that apparently

there is someone living on the moon that is behind the original stone beam, and they may or may not be nonhuman (i.e., aliens). Sapient aliens aren't impossible, but we don't know of any right now.